Auction Factory has 3 auction types defined based on which certain functions and features come into play.
These types are defined in [siteroot]/components/com_bids/bids.globals.php
1. Public Auctions
Regular auctions where every user and guest can see the latest bid, messages between the bidders and auctioneer.
2. Private Auctions
In private auctions, the only price shown to all users is the starting price. The highest bid is hidden from all others except the auctioneer and the respective bidder.
The bidders on the auction are hidden from others users, only the auctioneer having the option to see them.
There are two settings which override the private auction type, and those are: Max Bid (Show/Hide) and Nr. of Bidders (Show/Hide)
Messages are also hidden, the auctioneer can see all the messages and each bidder can see his own messages.
3. BIN Only (Buy it Now)
Auctions of this type have the regular bidding disabled and items can be sold in large quantities. This also allows auctioneers to receive suggestion prices for large quantities of items.